We have decided to move our pellet stove from the basement to the main floor of our house. We have a gas insert in the fireplace that we are going to connect our pellet stove to. We were told that we need to replace the piping going up the chimney with stainless steel pipe as the current piping is aluminum. Also was told that it needed to be 4". Looking for some input on this and also where is the best place to purchase piping....we need about 30' of it.